1. Field of the Invention
The present invention relates to an imaging device having a large number of photoelectric converting devices arranged on the same plane in a semiconductor substrate.
2. Description of the Related Art
An endoscopic apparatus including an image sensor of a CCD type or a CMOS type as an imaging device has already been used often on a medical site. The endoscopic apparatus is roughly divided into a frame sequential imaging method of using an imaging device capable of carrying out a monochromatic imaging to switch a filter for transmitting lights in wave ranges of R (red), G (green), B (blue) and IR (infrared) synchronously with a field frequency of the imaging device before a light source for illuminating an object through a fiber (for example, see Japanese Patent No. 2648494) and a simultaneous imaging method of picking up an image by using a single plate type imaging device mounting a color filter for transmitting the lights in the wave ranges of R, G and B with a white light set to be an illuminating light source.
The frame sequential imaging method serves to rotate a plurality of filters having different spectral transmittances before the light source and to pick up a plurality of images illuminated with lights having different wavelengths and to then synthesize a color image. For this reason, it is possible to obtain RGB color image data having information about three colors of RGB in one pixel data by using an RGB transmitting filter in a filter to be switched before the light source, for example. By sequentially switching an IR filter having two wavelengths which are apt to be absorbed into a hemoglobin in a blood and have bands narrowed, it is possible to obtain infrared image data causing one pixel data to have only information in an infrared region. According to an image based on the RGB color image data, it is possible to visually confirm an appearance of a portion to be an inspecting target. According to an image based on the infrared image data, it is possible to visually confirm information about a capillary vessel of a mucous membrane cortex and a mucous membrane fine pattern in the portion to be the inspecting target. In the frame sequential imaging, a color shift is generated for a moving object so that an image disturbance is caused.
On the other hand, the simultaneous imaging method serves to obtain the RGB color image data by an imaging and to then carry out an image processing over the RGB color image data, thereby generating infrared image data. According to the method, a color shift is not generated for a moving object. However, there is a problem in that precision in information of the infrared image data is low.
In the endoscopic apparatus, it is preferable that the RGB color image data causing one pixel data to have information about three colors of R, G and B and infrared image data causing one pixel data to have only information in an infrared region should be obtained by one imaging with high precision. However, there has not been proposed a method of obtaining the RGB color image data and the infrared image data by one imaging with high precision in the related art.